Asthma is the most common cause of respiratory disability in children. Asthma deaths have increased worldwide. one of the common factors associated with asthma fatality is failure to recognize the severity of the asthma attack. It can result in an inappropriate, even fatal, delay in receiving treatment. The primary goal of this project is to investigate the neural and behavioral mechanisms which contribute to this failure to recognize the severity of their asthma. specifically, the physiological processes mediating respiratory sensation and subsequent behavioral responses will be studied in asthmatic children. These studies will test the hypothesis that the perception of mechanical loads is related to respiratory related evoked potentials (RREP). The significance of the work lies in the fact that impaired perception of loaded breathing may put some asthmatic patients at risk by causing underestimation of the severity of an attack with consequent inadequate self-medication and delay in seeking medical attention. In addition, the RREP may serve as a neurological means of identifying patients with respiratory load sensory deficits. The RREP is a unique measure of cerebral cortical neural activity elicited by breathing against a mechanical load. This technique will be used, in combination with established psychophysical measures, to test for differences in the neural processing of respiratory load information between asthmatic and non-asthmatic children. The cortical distribution of the RREP and resistive load threshold for eliciting the RREP during inspiration and expiration will be determined. This will be followed by correlation of the neural measure of mechanical load afferent activation (RREP amplitude) with subjective measures of load perception. Elevated background resistance, such as occurs in chronic asthma, will be used to test for the change in perceptual sensitivity. The ventilatory response to mechanical loads will also be correlated with the RREP and detection of the load. The results of this project will provide new information on the sensory mechanisms mediating respiratory sensation in asthmatic and non-asthmatic children. In addition, a subgroup of severe asthmatics will be identified that have a reduced perceptual acuity for mechanical loads. These results will be used to develop a better physiological understanding of self-assessment sensitivity in these children and used to provide enhanced treatment strategies.